Abstract Significance: Trichotillomania (TTM), characterized by repeated pulling of one?s hair to the point of hair loss or thinning, produces impairment in physical, social, psychological and occupational functioning. Empirically supported treatment options for those with TTM are seriously limited. Among treatments shown to be effective is behavior therapy. Unfortunately, behavior therapy is limited in that developing real-time awareness of pulling remains challenging, there is a lack of widespread availability, and it typically has high cost. Hypothesis: It is hypothesized that a novel wrist-worn device and app system can be used to deliver Habit Reversal Therapy, a key component of behavior therapy, for trichotillomania. The device, using sophisticated motion sensors and algorithms, can be trained to detect an individual?s pulling behavior and thus augment awareness in real-time. Further, it can detect a competing response and build motivation via a user-friendly, feature rich mobile application. Preliminary Data: The investigative team?s device can record and detect a motion and orientation, representative of hair pulling behavior, reliably, per machine testing. Additionally, in one individual, a behavior of playing with eyebrows was reliably detected in >90% of cases with an acceptable rate (30%) of false positives for similar behaviors. Specific Aim 1: The ability of the device to accurately detect TTM-related behavior will be established and validated. The team will (1) catalog and record the range of motions that go into TTM-related pulling, and (2) refine and test the capacity of the device to accurately detect the motions in both simulated and human tests Specific Aim 2: Develop the HabitAware device and accompanying app as a stand-alone system for delivering self-administered HRT, utilizing an iterative process informed by expert end-user clinicians and persons with TTM. Specific Aim 3: The team will conduct an initial feasibility, usability and acceptability test of the HabitAware device to determine next steps and progress to a Phase II proposal. Long-Term Goal: We aim to develop a user-friendly, widely accessible and affordable system that helps treat trichotillomania via a device that provides real-time awareness of pulling behavior and a mobile app that incorporates elements of existing behavior therapy protocols.